SIMILARLY PROBLEMATIC for populations of migratory fish may well be the attempt by Meygen to exploit the tidal race in the Pentland Firth. The strait between Caithness and Orkney by which twice a day the Atlantic pours into the North Sea and vice versa. So ferocious is this current at its peak that even adult salmon cannot swim against it. The effect of underwater turbines on fish species has yet to be determined. It was partly to establish the evidence should discussions ever emerge about fish mortality or displacement arising from these turbines that the Caithness District Salmon Fishery Board initiated its programme of electric fishing all its rivers. To follow it up the Trust’s scientist, Alan Youngson, has written an original and highly important paper on the Firth entitled The Fishermen’s Knowledge: Salmon in the Pentland Firth. This will be found under Our Work.

THE EXISTENCE OF CLIMATE CHANGE is now accepted almost universally. If the outcomes are as most scientists predict, a number of risks need to be recognised. Some may arise from weather extremes such as drought and flood, both of which will impact severely on the Flow Country’s rivers which are, with the notable exceptions of the Naver and the Thurso, spate rivers. Of the two, drought will be the more harmful, or to be specific, river temperature. Salmon and sea trout begin to run into trouble when water temperature reaches about 20°C. For young fish, growth rate declines, then feeding ceases and at 25°C or so death occurs. Quiescent adults fare much better than fish which have been disturbed. Nevertheless, all salmon are in deadly peril by the time that stream temperature moves past 25°C. In fact there’s no reason to stop at salmon: all riverine species at our latitude are in danger when high temperatures coincide with low flows of water. The fish in the relatively small spate rivers of the Flow Country will be the first victims in prolonged periods of heat.

. . . It fills the county of Caithness and the eastern part of Sutherland. Its 1,500 square miles (4,000 sq. km.) make it the largest area of blanket bog in the world. It’s one of just three sites in Scotland listed as a possible UNESCO World Heritage Site. It’s kissed by the Gulf Stream. And it’s probably the easiest place in Britain to get lost in a snow storm. It’s also different for another reason: as the centre of the renewables industry. Various enterprises have been drawn there, principally by the favourable climatic conditions for wind farms and by the potential for producing tidal energy on a huge scale in the Pentland Firth.

The Flow Country Rivers Trust is a charity registered in Scotland. Its purpose is to promote and support initiatives, including research and education, to further the conservation of freshwater species of fish and associated flora and fauna within the Flow Country.

Causeymire Wind Farm

BLANKET BOG such as the Flow Country has several virtues as far as fisheries are concerned, all stemming from the poor natural drainage. A relatively constant water table is maintained; the speed of run-off in periods of high rainfall is markedly reduced; silt and harmful minerals are filtered out and invertebrates are able to enjoy a stable biozone. These are material advantages and will become more so if the recent pattern of extreme weather continues.

Since 1940 there has been a reduction of about 25% in Scotland’s blanket bog. The largest cause of this has been afforestation. A map of the forestry in the Flows is shown here.

Ploughing, draining and planting the deep peat of the Flows has done immense damage to the blanket bog and to many rivers. The logistics of felling and moving large quantities of timber will present a major challenge to all concerned if the damage wrought in the past is to be avoided. It is no exaggeration to say that whatever mankind does in the Flows has a profound effect on the river systems that arise in them.

GEOLOGICALLY SPEAKING, the Flows consist of a largely flat expanse of peat, often to a great depth, laid over sandstone in Caithness merging with granite and then gneiss in eastern Sutherland. (See map). The result is mile after mile of rough, wet, awkward land studded with small lochs and often lacking a clear indication of the natural fall of the land. The Wick river, for instance, drops only 390 feet (100m) between its source and where it enters the sea, a distance of 25 miles (40 km). Its gradient from Watten to the ocean is 1 in 800. Because of the underlying platform of rock and the flatness of the terrain, drainage is poor and the water table high. This is the essential character of the Flow Country.

On the coastal margins of both Caithness and Sutherland, there are some terrific cliffscapes and beaches. These cliffs, their ledges glazed by centuries of droppings, are host to a vast tumult of nesting sea birds. In the summer breeding season, the Flows support a wide range of migratory birds, many of which are not commonly seen. In all, the area within the remit of the Trust covers several hundred miles of coastline, thirteen salmon rivers, hundreds of brown trout lochs, including the famous Loch Watten, plus colonies of Arctic char and freshwater pearl mussels of international significance. Despite the various encroachments of mankind , there has been as yet no loss of species or of structural diversity. The Flows remain one of the most pristine areas of the north.

The 2013 review by RAFTS and ASFB included a piece from a director of the River Dee Trust stating that water temperatures above 25°C were now occurring “routinely”. In 2007 one of their biologists reported a temperature of 27°C. Marine Scotland Science (MSS) says a 2°C rise in average water temperatures has happened over the last thirty years on the Dee. Closer to home, the comprehensive electric-fishing survey of the Caithness rivers that took place in the autumn of 2013 showed that many of the parr captured had suffered checks in growth, probably as a result of the exceptionally hot weather and low water in July that year.

Irrespective of the causes of global warming, it’s here to stay. One would need to have a very long horizon to believe otherwise. With it will come change in many forms. Weather-wise, the past has ceased to be a guide to the future. None of us knows what lies ahead. We should therefore gather together all the knowledge that we can about our rivers and lochs and the species that inhabit them, in fact about everything that could have a bearing, maybe fifty years out, on the measures needed to help them through trouble. Nothing on this scale has been attempted before. Without question it will turn into an entire gazetteer of possibilities. With this in mind the Trust’s Scientific Advisor haswritten a paperon the steps that need to be taken and the benefits to be derived.

The Atlantic salmon is a flagship species, one of the few. Had it not been able to adapt to the climate change we’ve had in the past, it would have disappeared long ago. But those were changes that occurred at a leisurely pace. The warming that we’re now experiencing is happening rapidly. There are already species such as the Russian sturgeon and the river dolphin that are either too low in number to sustain their populations or are unable to keep up with the rate of change in their environment. They are officially labelled “endangered” but in fact they are trapped in the vortex of extinction and one could write out their death certificates tomorrow.

Are we to let the wild Atlantic salmon go the same way? Shrug our shoulders and say “Who cares?” as one of our truly great assets disappears? Of course not. We must therefore do everything that is humanly possible, and then some more, for it and its close relative the sea trout. The fact that they must adapt at a speed far faster than they ever have done before must not discourage us. We must help them. We must improve our rivers. We must look at all the species in our rivers and lochs and see how, taking advantage of everything that science and money has to offer, we can help safeguard their future. That’s the business of the Flow Country Rivers Trust and that’s why it needs your support.

AMONG THESE ENCROACHMENTS are numerous wind farms. Not only are the average annual wind speeds in Caithness among the highest in Europe but the blow is “clean”, being unimpeded by natural features. Wind farms involve excavation of the peat for the construction of turbine bases, roads and bridges. In the Flows, each turbine base displaces about 5,000 tons of peat, a figure that is by no means negligible. In the dry, breezy conditions of summer, when most of the work has to be done, peat becomes friable and unless handled responsibly is liable to end up as sediment in the local watercourses and thus silt up the redds in which salmon deposit their ova. So delicate is the ecology of the Flows that it takes little to alter the chemistry of their streams and thus their water quality. At present it appears that the emphasis is changing from onshore to offshore wind farms but this may create a whole new range of problems for migratory fish since they appear to take their bearings from a number of factors such as wave noise, tides and currents of which we know little.